Back now with the story behind the unusual sight in Maine. A giant floating disc of ice spinning in a refer fascinating and perplexing people all across the country and T.J. Holmes, the best one to send there for it all. Hey there, T.J. Reporter: You don't need to, robin, go to the great pyramids of Giza, we have found our own eighth wonder of the world in Maine. Robin, I give you ice. I know what you're thinking. T.J., I've seen ice before but I assure you you've never seen ice like this. An estimated 100 yard across perfectly formed circle of ice that's in the middle of a river in the middle of the town of Westbrook. I know you're glued to your screens right now but I beg you, don't stare too long. It's slowly spinning. It's spinning in a circle. I don't want you to get lost in its hypnotic powers. They have used it as a promotional tool in town. This is the most exciting thing to happen in Westbrook since, okay, this is the most exciting thing to ever happen in the town of west many brook. They are hoping it's going become a tourist attraction. People are just fascinated. I have the mayor here with me. Mayor sanphy, are you trying to use this to put you guys on the map as a promotional tool here? Yes, we are. You are. You think it will draw people to your town. I hope it will. We're very proud to that. It's very unique. I never seen one before but I'm glad to have it here. Some folks are saying it looks like a crop circle in the water. Alien intervention, because it's spinning, hey, we need one more turntable and a meek phone. Whatever you think about it, I am not the expert. I want to turn back to you guys and, ginger, who can better explain the phenomenon of water freezing. Yes, water does freeze. Thank you, T.J., for that part. That started us off well. But they've actually happened before. I've shown them to you. A couple years ago one happened in Michigan so ice discs do occur. It's been a couple of years since they figured out why, though, so we know the ice break as part and used to think it was the current of the river that turned it and smoothed it out. Not so. We have figured out that when these do form it is the ice melting that cold water that comes from it heads down in the river and then that spins it at a constant rate so that's a big one. We know that but there are others and all spin at similar rate.

This transcript has been automatically generated and may not be 100% accurate.

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